The present invention relates to a magnetic disc storage device, and more particularly to a magnetic disc storage device capable of reading and writing data to a magnetic disc which is on rotation.
The conventional magnetic disc storage device is disclosed in the Japanese laid-open patent publication No. 59-21248. The magnetic disc storage device has a spindle motor which rotates magnetic discs, and magnetic heads which are positioned adjacent to surfaces of the rotating magnetic discs for reading and writing data to the magnetic disc which is rotating. The spindle motor, the magnetic discs and the magnetic heads are accommodated in a housing. The housing comprises a base plate and a cover member. The spindle motor is provided with a motor main shaft which is fixed to the base plate and a hub which rotates around the motor main shaft. The magnetic discs are co-axially fixed to the hub. A head carriage is provided which is rotatable around a carriage main shaft so that the head carriage can move the magnetic head in generally radial direction of the magnetic disc. The top of the motor main shift is fixed via a screw to the cover member of the housing. The hub is rotatably attached via ball bearings to the motor main shaft.
The above magnetic disc storage device has a serious problem as follows. When the spindle motor rotates around the motor main shaft, a vibration appears on the ball bearings. This vibration is transmitted through the motor main shaft to the cover member of the housing. As a result, the cover member of the housing is vibrated to generate an undesirable noise.
In the above circumstances, it had been required to reduce the noise generated by vibration of the cover member of the housing, which has been transmitted through the motor main shaft from the ball bearings.